An MBMS (Multimedia Broadcast Multicast Service) is used to provide a multimedia broadcast service and a multimedia multicast service for user equipment (UE) in a cell. The multimedia broadcast service may broadcast multimedia video information to all UEs, and the multimedia multicast service may send some paid multimedia video information to a group of subscribed UEs for watching.
In an LTE (Long Term Evolution) system, when an MBMS mode is used to transmit a physical multicast channel (PMCH), a network side device needs to modulate, according to a preset modulation scheme, a PMCH that needs to be transmitted, so as to obtain a modulated signal, and sends the modulated signal according to preset transmit power. After receiving the modulated signal, UE needs to decode, according to configuration information such as the preset transmit power, the received modulated signal.
Because a channel environment quality between cell edge UE and a base station is relatively poor (a signal-to-noise ratio is relatively low), a low-order modulation scheme, for example, Quadrature Phase Shift Keying (QPSK), needs to be used when service data is transmitted to the cell edge UE, so as to ensure robustness of service transmission. Because a channel environment quality between cell center UE and the base station is relatively high (the signal-to-noise ratio is relatively high), a high-order modulation scheme, for example, 16 QAM or 64 QAM, may be used when service data is transmitted to the cell center UE, so as to increase a bit rate of signal transmission. In the LTE system, when MBMS data is broadcast to all UEs in the cell, only a low-order modulation scheme can be selected, so as to ensure that the cell center UE and the cell edge UE can both receive the MBMS data. As a result, an overall system throughput is reduced, which results in relatively low system spectrum utilization efficiency.